1. Field of the Invention
The present invention relates to the cooling of the cylinder and cylinder head assemblies of air-cooled engines and compressors. In particular, the invention is directed to a shroud for increasing the efficiency of the cooling airflow from a fan to the assemblies of cylinders and cylinder heads.
2. Description of Related Art
In U.S. Pat. No. 2,150,912 to Clapp, an arrangement for improving the cooling effect of air displaced by a cooling fan of an air compressor is disclosed wherein a shrouding of the compressor is provided in the form of a shrouding box which sits over the cylinder heads and on top of the compressor block, and which has a double wall construction, the inner walls of which converge toward an outward end of the box at which an opening for the egress of air from the rear of the shrouding box is provided. In this way, only some of the air which is channeled into the shrouding box from the cooling air fan by supporting side wall plates of an enclosure for the cooling air fan passes over the fins of a first of two axially arranged cylinder heads while all of the air is forced over the fins of the downstream, second cylinder head, before being discharged through the egress opening of the shrouding box. However, such a double wall enclosure is relatively expensive to produce and the particular arrangement of Clapp is only suitable for arrangements wherein the cylinder heads are arranged in a line along the axis of the fan, as opposed to situations wherein, for example, the cylinder heads are in an array that is in a plane oriented perpendicular to the flow axis.
In U.S. Pat. No. 1,944,878, a cowling or shrouding for an annular array of cylinder heads of an air-cooled aircraft engine is disclosed. This airflow-control cowling is of a conoidal shape for increasing the flow of air that passes around and between the cylinders to cool them, and while no particular baffle arrangement is shown or described, it is taught that the effectiveness of the cowling can be increased through the use of baffles near the engine cylinders to force the airflow over the hotter parts of the cylinders. This cowling is supported by being attached to the cylinder heads of the engine by supporting struts. However, this cowling is relatively large and is particularly designed for use with aircraft engines having push and pull type propellers. It does not suggest a simple, inexpensive and efficient means for producing a comparable effect for air-cooled multicylinder engines which are supported upon the ground and thus do not have an annular array of cylinders, nor does it disclose a cowling which creates an orifice effect that avoids wasting of cooling air and increases the surface area of the cylinders over which the cooling air flows.
Examples of other arrangements for improving the guiding of cooling air over cylinder head assemblies of air-cooled multicylinder internal combustion engines are shown in U.S. Pat. Nos. 3,017,943 and 4,204,486. However, these arrangements are relatively complex and are designed to substantially enclose the entire area of the engine from around the entire periphery of the cooling fan to the area surrounding the cylinder head assembly.
Thus, there is still a need for a simple, inexpensive and efficient cowling for improving the cooling of cylinder and cylinder head assemblies of air-cooled engines, such as reciprocating air and gas compressors having an arcuate array of cylinder heads disposed about the axis of flow from a cooling air fan, that can be easily added onto existing cylinder head assemblies (as well as removed for service) without significantly increasing either the size of the overall arrangement.